1. Field of the Invention
The present invention generally relates to a supporting apparatus for supporting a magnetic head slider in a floating manner relative to a magnetic disc, and more particularly, it relates to an in-line type magnetic head supporting apparatus so constructed that a longitudinal direction of a load beam of a head supporting mechanism coincides with the circumferential direction of the disc.
2. Description of Related Art
In a magnetic head slider used in a magnetic disc system, in order to read data accurately, the attitude of the magnetic head slider must follow dynamic displacements of the magnetic disc such as surface vibrations generated at the rotating movement. To this end, an arrangement has been conventionally disclosed, for example, in Japanese Patent Publication No. 22827/1983. FIG. 1 is a perspective view showing a general magnetic head supporting apparatus, and FIG. 2 is an exploded perspective view showing essential portions of a prior art magnetic head supporting apparatus. In FIGS. 1 and 2, numerals 1 through 7 indicate a magnetic head slider mounted with a magnetic head (not shown), 2 a gimbal mechanism, 2a a U-shaped spring part of the gimbal mechanism, 3 a magnetic disc, 4 a load beam, 5 a first fixed part secured to the magnetic head slider 1, 6 a second fixed part secured to the load beam 4 of the gimbal mechanism and 7 a pivot which is a convex portion and formed in the first fixed part 5, respectively. The load beam 4 is in contact with the pivot 7 at a contact point 4a. Also, in FIGS. 1 and 2, a direction X shows the radial direction of the magnetic disc 3, a direction Y indicating the circumferential direction thereof, while a direction Z is a pressing direction to which the magnetic head slider 1 is pressed against the magnetic disc 3, and is orthogonal to the directions X and Y. An arrow A indicates the rotating direction of the magnetic disc 3 and an arrow B represents the moving direction of the magnetic head. The load beam 4 is elongated in the circumferential direction of the magnetic disc 3 or in the direction Y, pressing the magnetic head slider 1 via the pivot 7 of the gimbal mechanism 2 toward the magnetic disc 3, that is, in the direction Z. The gimbal mechanism 2 is, for example, bonded to the magnetic head slider 1 at the first fixed part 5. Also, the second fixed part 6 on the rear end of the gimbal mechanism 2 is secured to the load beam 4 through bonding by, such as, spot welding or the like.
The magnetic disc 3 is rotated in a direction shown by the arrow A and the magnetic head slider 1 is moved in a direction shown by the arrow B. The magnetic head slider 1 is supported by the gimbal mechanism 2 for pitching and rolling movements in the radial (X-axis) and circumferential (Y-axis) directions of the magnetic disc 3, and so constructed as to let the attitude these of follow dynamic variations of the magnetic disc 3. When the magnetic disc 3 is rotated, an air spring actuated by the air flowing in between the magnetic disc 3 and the magnetic head slider 1 is produced. In order to place or add a load necessary to maintain the balance of force with the air spring onto the magnetic head slider 1, the load beam 4 is in contact with the pivot 7 at the contact point 4a thereby to press the magnetic head slider 1.
Since the prior art magnetic head supporting apparatus is constructed as mentioned hereinabove and when the magnetic head slider 1 is moved at high speeds, for example, in the direction B, the gimbal mechanism 2 experiences added pressure in the direction X, resulting in deformation of a spring part 2a of the gimbal mechanism 2. FIG. 3 is a plan view showing an example of the deformation of the spring part 2a of the gimbal mechanism 2, in which a solid line indicates the deformed gimbal mechanism and a broken line shows the normal one. Since the pressure in the direction X is applied directly to the pivot 7 which is the contact point with the load beam 4, the spring part 2a is deformed, causing the pivot 7 to slip sideways in the direction X. FIG. 4 is a graph showing an acceleration transmission function of the magnetic head slider 1 in the direction X with respect to the driving force of the magnetic head supporting apparatus using a deformed gimbal mechanism 2, in which X-axis designates the frequency (kHz) of the driving force. Y-axis indicates the phase (degree) in FIG. 4(a) and the gain (dB) in FIG. 4(b) respectively. As shown in FIG. 4, a resonance peak in the bending mode of the gimbal mechanism 2 in the direction X is found at the frequencies of 1.7 kHz to 2.1 kHz. Therefore, the conventional apparatus encounters such problems that the driving force is not transmitted correctly and a positioning control system becomes unstable. It is to be understood that the aforesaid frequency varies depending on the size of the head and the construction of a suspension.
For preventing the sideslip of the pivot 7 referred to above, a prior art has been disclosed in Japanese Patent Application Laid-Open No. 65275/1987. In this invention, in order to prevent the abrasion of the pivot of the right angle type magnetic head in which the load beam is elongated in the radial direction of the magnetic disc, a dimple having a radius of curvature larger than that of the pivot and a depth not exceeding the projected height thereof is formed at the contact point of the load beam with the pivot.
In the aforementioned prior art, however, it is annoying to form the dimple in the load beam. Moreover, in the right angle type magnetic head supporting apparatus, though the sideslip may be prevented by the dimple since the bending moment applied to the gimbal mechanism is smaller, in case of the in-line type, the large bending moment is applied to the gimbal mechanism, which makes it difficult to prevent the sideslip of the pivot.
As shown in FIG. 5, when the first fixed part 5 secured to the magnetic head slider 1 is pressed out by pressing, since it is not on the same plane as the other surface of the gimbal mechanism, an application of force in the direction X results in the fact that the spring part 2a between the first and second fixed parts 5, 6 is exposed to the torsional force and bent to be weak in the direction X.
Accordingly, it was problematic that characteristics at positioning of the magnetic head slider 1 are badly influenced.